/*  Starshatter OpenSource Distribution
    Copyright (c) 1997-2004, Destroyer Studios LLC.
    All Rights Reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    * Neither the name "Destroyer Studios" nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

    SUBSYSTEM:    Stars.exe
    FILE:         FlightComp.cpp
    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    Flight Computer System class
*/

#include "MemDebug.h"
#include "FlightComp.h"
#include "Ship.h"
#include "ShipDesign.h"
#include "Thruster.h"

// +----------------------------------------------------------------------+

FlightComp::FlightComp(int comp_type, const char* comp_name)
: Computer(comp_type, comp_name), mode(0), vlimit(0.0f),
trans_x_limit(0.0f), trans_y_limit(0.0f), trans_z_limit(0.0f), 
throttle(0.0f), halt(0)
{ }

// +----------------------------------------------------------------------+

FlightComp::FlightComp(const Computer& c)
: Computer(c), mode(0), vlimit(0.0f),
trans_x_limit(0.0f), trans_y_limit(0.0f), trans_z_limit(0.0f), 
throttle(0.0f), halt(0)
{ }

// +--------------------------------------------------------------------+

FlightComp::~FlightComp()
{ }

// +--------------------------------------------------------------------+

void
FlightComp::SetTransLimit(double x, double y, double z)
{
    trans_x_limit = 0.0f;
    trans_y_limit = 0.0f;
    trans_z_limit = 0.0f;

    if (x >= 0) trans_x_limit = (float) x;
    if (y >= 0) trans_y_limit = (float) y;
    if (z >= 0) trans_z_limit = (float) z;
}

// +--------------------------------------------------------------------+

void
FlightComp::ExecSubFrame()
{
    if (ship) {
        ExecThrottle();
        ExecTrans();
    }
}

// +--------------------------------------------------------------------+

void
FlightComp::ExecThrottle()
{
    throttle = (float) ship->Throttle();

    if (throttle > 5)
    halt = false;
}

// +--------------------------------------------------------------------+

void
FlightComp::ExecTrans()
{
    double tx = ship->TransX();
    double ty = ship->TransY();
    double tz = ship->TransZ();

    double trans_x = tx;
    double trans_y = ty;
    double trans_z = tz;

    bool flcs_operative = false;

    if (IsPowerOn())
    flcs_operative = Status() == System::NOMINAL ||
    Status() == System::DEGRADED;

    // ----------------------------------------------------------
    // FIGHTER FLCS AUTO MODE
    // ----------------------------------------------------------

    if (mode == Ship::FLCS_AUTO) {
        // auto thrust to align flight path with orientation:
        if (tx == 0) {
            if (flcs_operative)
            trans_x = (ship->Velocity() * ship->BeamLine() * -200);

            else
            trans_x = 0;
        }

        // manual thrust up to vlimit/2:
        else {
            double vfwd = ship->BeamLine() * ship->Velocity();

            if (fabs(vfwd)>= vlimit) {
                if (trans_x > 0 && vfwd > 0)
                trans_x = 0;

                else if (trans_x < 0 && vfwd < 0)
                trans_x = 0;
            }
        }

        if (halt && flcs_operative) {
            if (ty == 0) {
                double vfwd     = ship->Heading() * ship->Velocity();
                double vmag     = fabs(vfwd);

                if (vmag > 0) {
                    if (vfwd > 0)
                    trans_y = -trans_y_limit;
                    else
                    trans_y = trans_y_limit;

                    if (vfwd < vlimit/2)
                    trans_y *= (vmag/(vlimit/2));
                }
            }
        }


        // auto thrust to align flight path with orientation:
        if (tz == 0) {
            if (flcs_operative)
            trans_z = (ship->Velocity() * ship->LiftLine() * -200);

            else
            trans_z = 0;
        }

        // manual thrust up to vlimit/2:
        else {
            double vfwd = ship->LiftLine() * ship->Velocity();

            if (fabs(vfwd) >= vlimit) {
                if (trans_z > 0 && vfwd > 0)
                trans_z = 0;

                else if (trans_z < 0 && vfwd < 0)
                trans_z = 0;
            }
        }
    }

    // ----------------------------------------------------------
    // STARSHIP HELM MODE
    // ----------------------------------------------------------

    else if (mode == Ship::FLCS_HELM) {
        if (flcs_operative) {
            double compass_heading = ship->CompassHeading();
            double compass_pitch   = ship->CompassPitch();
            // rotate helm into compass orientation:
            double helm            = ship->GetHelmHeading() - compass_heading;

            if (helm > PI)
            helm -= 2*PI;
            else if (helm < -PI)
            helm += 2*PI;

            // turn to align with helm heading:
            if (helm != 0)
            ship->ApplyYaw(helm);

            // pitch to align with helm pitch:
            if (compass_pitch != ship->GetHelmPitch())
            ship->ApplyPitch(compass_pitch - ship->GetHelmPitch());

            // roll to align with world coordinates:
            if (ship->Design()->auto_roll > 0) {
                Point vrt = ship->Cam().vrt();
                double deflection = vrt.y;

                if (fabs(helm) < PI/16 || ship->Design()->turn_bank < 0.01) {
                    if (ship->Design()->auto_roll > 1) {
                        ship->ApplyRoll(0.5);
                    }
                    else if (deflection != 0) {
                        double theta = asin(deflection);
                        ship->ApplyRoll(-theta);
                    }
                }

                // else roll through turn maneuvers:
                else {
                    double desired_bank = ship->Design()->turn_bank;

                    if (helm >= 0)
                    desired_bank = -desired_bank;

                    double current_bank = asin(deflection);
                    double theta = desired_bank - current_bank;
                    ship->ApplyRoll(theta);

                    // coordinate the turn:
                    if (current_bank < 0 && desired_bank < 0 ||
                            current_bank > 0 && desired_bank > 0) {

                        double coord_pitch = compass_pitch 
                        - ship->GetHelmPitch() 
                        - fabs(helm) * fabs(current_bank);
                        ship->ApplyPitch(coord_pitch);
                    }
                }
            }
        }

        // flcs inoperative, set helm heading based on actual compass heading:
        else {
            ship->SetHelmHeading(ship->CompassHeading());
            ship->SetHelmPitch(ship->CompassPitch());
        }

        // auto thrust to align flight path with helm order:
        if (tx == 0) {
            if (flcs_operative)
            trans_x = (ship->Velocity() * ship->BeamLine() * ship->Mass() * -1);

            else
            trans_x = 0;
        }

        // manual thrust up to vlimit/2:
        else {
            double vfwd = ship->BeamLine() * ship->Velocity();

            if (fabs(vfwd) >= vlimit/2) {
                if (trans_x > 0 && vfwd > 0)
                trans_x = 0;

                else if (trans_x < 0 && vfwd < 0)
                trans_x = 0;
            }
        }

        if (trans_y == 0 && halt) {
            double vfwd     = ship->Heading() * ship->Velocity();
            double vdesired = 0;

            if (vfwd > vdesired) {
                trans_y = -trans_y_limit;

                if (!flcs_operative)
                trans_y = 0;

                double vdelta = vfwd-vdesired;
                if (vdelta < vlimit/2)
                trans_y *= (vdelta/(vlimit/2));
            }
        }



        // auto thrust to align flight path with helm order:
        if (tz == 0) {
            if (flcs_operative)
            trans_z = (ship->Velocity() * ship->LiftLine() * ship->Mass() * -1);

            else
            trans_z = 0;
        }

        // manual thrust up to vlimit/2:
        else {
            double vfwd = ship->LiftLine() * ship->Velocity();

            if (fabs(vfwd) > vlimit/2) {
                if (trans_z > 0 && vfwd > 0)
                trans_z = 0;

                else if (trans_z < 0 && vfwd < 0)
                trans_z = 0;
            }
        }
    }

    if (ship->GetThruster()) {
        ship->GetThruster()->ExecTrans(trans_x, trans_y, trans_z);
    }
    else {
        ship->SetTransX(trans_x);
        ship->SetTransY(trans_y);
        ship->SetTransZ(trans_z);
    }
}
